Switch



F. HOTCHNER Dec. 13, 1932.

SWITCH Filed Nov. 21, 1930 INVENToR Patented Dec. 13,1932 1,890,510

UNITED STATES PATENT OFFICE FRED HOTCHNEBQ, OF LOS ANGELES, CALIFORNIA SWITCH Application filed lovember 21, 1930. Serial No. 497,165.

This invention relates to a switch in which A particular embodiment of the invention the insulating character of an extremely thin shown also provides certain useful features layer of gaseous conductor is utilized for the of construction hereinafter described. purpose of breaking a circuit. While I set forth herein a theory of the It is known that in a discharge tube conoperation of the device it is to be understood taining an ionization conductor and a pair that the invention is not tobe limited thereof opposing spaced electrodes between the by. near opposing surfaces of which the dis- The invention is illustrated by the precharge is confined a certain minimum disferred embodiment shown in the accompany- 19 tance is required between the opposing suring drawing, but it is to be understood that faces in order that conduction may take place. I do not intend to be limited to the particu- For instance in helium gas at a pressure of lar details shown, since many changes and two millimeters of mercury when the dismodifications may be made and the inventance is reduced to one millimeter between tion embodied in widely different forms 15 the surfaces conduction virtually ceases. Acwithout departing from the spirit and scope cording to commonly accepted ideas today thereof in its broader aspects. Hence I dethis distance is that at which an electron sire to cover all modifications and forms leaving the cathode travels before it hits an coming within the language and scope of atom of the contained gaseous medium. In any one or more of the appended claims.

20 other words it would be that distance in In the drawing:

which insufiicient collisions occur to set up Fig. 1 is an elevation of a switch made acthe ionization necessary for free conduction, cording to this invention. and is considered to be in the order of the Fig. 2 is a cross section through the axis mean free path of the molecules of the conof the tube shown in Fig. 1. i p tained gas. A certain very small current Fig. 3 is a perspective view partly broken may flow under conditions where there is away, of the movable element of the switch no ionization, but for all practical purposes shown in the preceding views. thiscurrent can be neglected. Referring more particularlyv to the draw- Broadly the invention has for its object ing, 1 indicates an envelope which is evacu- 30 the utilization of this phenomenon in a ated and provided with a body of gas preferswitch for making and breaking a circuit. bl at a low pressure and capable of convey- More specifically it has for its object the proi g current by ionization at low voltages. duction of a device in which the technical A i ell known in the art, under certain conconditions necessary to insure a clean make ditio a, very thi layer f i i ti and break action are r aliz d with a minlductor may become an excellent insulator. mum of complicating fac or and in an 3P- The exact figure for the thickness of this layer paratus capable of quantity product n Wlth varies with different gases under different 8 g degree of uniformity in performanceconditions but, as ordinarily understood, it is It is an object of this invention to disclose f i -1 close t th l th f th mean f 0 and provide an ionization conductor swltch th f th molecules f th Th f that y be Simple, efficient and y to two electrodes are provided within the enfabricate. I I velope 1, the electrode 3 being stationary and Another Object of thls inveyltwn to (113' being provided with a lead-in conductor 4 close and Provide a constructlon whlch P which extends through a reentrant stem 5 and mits accurate adjustment y Visual methodsis soldered onto the ferrule 6 at the point 7, 95

A still further object of this invention is thereby idi t t t l t t to disclose and provide a mounting for a side of the envelope 1. The other electrode switch of the type described by means of 8 is slidable upon the lead-in conductor 9 which the device may be operated by rotamaking contact with it at all times through 50 tion. the spring contact 31. The conductor 9 extends through the reentrant stem andconnects with the ferrule llat the point 12. The ferrules 6 and 11 have extended portions 13 and 14 overlapping each other with respect to the axis of rotation A-A around which the tube is disposed to be rotated on the spindles 15 and 16, the electrode 8 thereby being caused. to move by gravity toward or away from the electrode 3. The boss 17 on the end of the lead-in conductor 9 serves to limit the movement of the electrode 8 in both directions parallel with the axis of the tube, by cooperating with the end 20 of the electrode 8 and the cross bar 21. The space 22 between the approaching faces 23 and 24 of the electrodes is sufliciently small that conduction cannot take place between the two electrodes upon the application-of any voltage which the switch is-intended to operate on. If the tube is charged with helium gas at two millimeters of mercury pressure this distance should be under one millimeter. The diameter of the electrodes should be fairly large as compared with this dimension to insure that virtually all lines of force between the two electrodes are straight. Thus a diameter of one inch at a spacing of one millimeter and at a pressure of two millimeters in helium provides a condition in which so few lines of force terminate on the wall of the tubeor are distorted by external conditions that the insulating effect is unimpaired by secondary conthe end of the Faraday dark space, which is visible toordinary inspection. It .will be found to vary considerably under different conditions and is usually from one half inch to an inch and a half. p Certain conditions must be observed in fabricating a device of this character in order to secure economical production and a uniform product. 4 The glass tube must have an inside diameter only slightly greater than the outside diameter of the electrodes, that is, just suflicient to allow the electrodes to expand during the process of degasification without applying pressure to the glass tube. The electrodes should be as thoroly degasified as possible before assembling the device in order that they need not be raised to a very high temperature when completing the switch. Thus the danger of melting the glass envelope is reduced and further a closer fit may be observed if it is not necessary to allow extra space for the expansion of. the electrode. The space between the electrodes and the glass tube must also never exceed that dimension which would allow a flash over to occur past the electrode. It is necessary 'to insure that the discharge be confined to flashes back between the electrodes and the wall of the tube to the rear of the electrodes or lead in wires thetube will freely conduct at all times. In order to insure that the space between the electrode and the wall does not in itself act as a cathode care should be taken that no deposit of metal is formed on the glass during fabrication, as under such conditions the discharge somtimes becomes localized to the cavityin preference to the adjacent exposed surfaces. Ihave found that by activating a surface such as the opposin surfaces 23 and 24 while leaving other adjacent surfaces in their natural condition the danger of the discharge wandering to the undesired surfaces is greatly reduced. Thus an activating coating of any In fabricating the device, the space 22 may 7 be visually determined and ad]usted man uall by the simple device of heatin one of t e ends of the tube and pressin t e reentrant stem in or out until the e ectrodesare the correct distance apart. The ferrules 6 and 7 are secured to the tube with ordinary basing cement.

The device is evacuated at the tubulation 30 in the usual manner. The electrodes may be de-gasified by high frequency induction or by bombardment and the tube may be charged with the necessary ionization conductor by the methods well known in the art. .By the term ionization conductor as used herein I have reference to any fluid capable of sustaining aglow discharge and conveying current by the process of ionization. Typical of such fluidsare the rare gases at low pressures and'the vapors of metals.

By the term low 'dischar herein I have reference to a discharges which take place through a fluid upon the application of electric otential across a body thereof resulting in t e flow of current by the ionization of the molecules or atoms of said fluid which is characterized by the factthat a thin layer of said fluid close to the cathode acts as an insulator when itis mechanically divided from the main column -of fluid in the device. It is to be here noted that this definition of a'glow discharge does not necessarily coincide with thatdefinition commonly used in the literature to distinguish one particular type of discharge from.

arc, coronas, or transitory types of discharge, but may include or overlap such other types under certain conditions within the purview j of this invention. Nor is this definition to be understood as conditioned uponthe appearance of a visible glow, as the condition herein contemplated may exist without the emission of visible radiation.

By the term parallelly disposed opposing as used.

surfaces as herein used or other terms of the like purport it is to be understood that I am not limiting my devices to electrodes having plane parallel surfaces but I intend to include in this term surfaces which are conformed to compensate for electric field conditions such as condenser plates that are rounded at the edges, and I also intend to include such surfaces as depart from parallelism by an amount not inimicalto the realization of the phenomenon herein described and the functioning of the device.

The invention is not limited to the embodiment as shown but may be variously embodied in ionization conductor devices and is to be limited only by the prior art and the appended claims.

Having thus described my invention, what I claim is:

1. In a switch, a tube of insulating material hermetically sealed and provided with an atmosphere of gaseous ionization conductor, cylindrical electrodes in said tube, at least one of which is slidable through said tube but fitting the inside wall of said tube so close as to prevent the discharge passing therebetween, and means to limit the movement of said electrode in two directions whereby said electrode may approach the other electrode so closely that no conduction may take place therebetween upon the application of voltage to said electrodes by virtue of the insulating effect of a thin layer of the ionization conductor.

2. In a switch a tube of dielectric material, electrodes within said tube having parallel disposed opposing surfaces, a gaseous ionization conductor in said tube, and means to vary the distance between said electrodes so that said electrodes may be brought together so close without touching that the layer of gas between the said op osing surfaces is non-conducting or may e separated to a greater distance such that the layer of gas remaining therebetween is conducting.

3. The method of making and breaking a circuit which consists in varying the distance between two electrodes immersed in a gaseous ionization conductor between twolimits without touching, the lesser of which distances is so selected that the layer of said conductor remaining between the opposing surfaces of said electrodes is non-conducting.

4. A switch comprising an envelope, a gaseous ionization conductor therein, a pair of electrodes therein, conducting means providing contact between said electrodes and the outside of said envelope, and means to vary the distance between saidelectrodes between two limits without said electrodes touching at any time to make direct contact, the lesser of said limits being of such low value that when quality of the thin layer of ionization conductor remaining therebetween, and the greater of said limits being of such high value that when the electrodes are so positioned and sufficient potential is applied thereto to cause ionization in said conductor free conduction takes place through said switch by virtue of material conduction takes place therebetween by virtue of the insulating quality of the thin layer of ionization conductor remaining therebetween, and the greater of said.

limits being of such high value that when the electrodes are so positioned and sutficient potential is applied thereto to cause ioniza tion in said conductor tree conduction takes place through said switch by virtue of the ionization of the contained medium between said electrodes.

6. A switch comprising an envepole, a gas eous ionization conductor therein, a pair of electrodes therein having parallelly disposed and opposing emitting surfaces, conducting means providing contact between said electrodes and the outside oi said envelope, means to confine the discharge to the medium between said surfaces, and means to vary the distance between said electrodes between two limits without said electrodes touching at any time to make direct contact, the lesser of said limits bein of such low value that when the electro es are so positioned and potential is applied thereto no material conduction takes places therebetween by virtue of the insulating quality of the thin layer of ionization conductor remaining therebetween, and the greater of said limits being of such high value that when the electrodes are so positioned and 'sufiicient potential is applied .thereto to cause ionization in said conductor free conduction takes place through said switch by virtue of the ionization of-the contained medium between said the electrodes are so positioned and potential is applied thereto no material conduction takes place therebetween by virtue of the insulating 

